The client connection device for the UPS system is used in a high-power UPS with high power density, and mainly includes a battery distribution unit, a main input distribution unit, a bypass input distribution unit, and an output distribution unit. In the prior art, the respective units as mentioned above are arranged side by side. That is, the battery distribution unit, the main input distribution unit, the bypass input distribution unit, and the output distribution unit are lined up, in which a battery input EMI (ElectroMagnetic Interference) board and battery input copper bars in the battery distribution unit are disposed vertically on the right side. Such arrangement causes the device to occupy a relative large space in a cabinet, especially a relative large transverse space in the cabinet. Thus, the whole volume of the cabinet is relative large and the transverse width thereof is relative wide, which is inconvenient for the arrangement and installation of the device.